In the manufacture of electronic devices, it may be required to selectively etch one region, among two regions each formed of different materials, with respect to the other region. For example, a first region, among two regions, is formed of silicon nitride, and a second region, among the two regions, is formed of silicon oxide.
In order to selectively etch the first region, formed of silicon nitride, with respect to the second region formed of silicon oxide, plasma etching using a hydrofluorocarbon gas is generally performed. In the plasma etching using the hydrofluorocarbon gas, the first region is etched by an active species in the plasma while the second region is protected by a deposit of fluorocarbon. Such plasma etching is described in Japanese Laid-Open Patent Publication No. 2003-229418.